Electric oven



Nov. 19, 1929.

R. H. MaClNNES,

ELECTRIC OVEN Filed Aug. 29. 1921A I5 Sheets-Sheet 2 l, l l @AM R. H. MaClNNES ELECTRIC OVEN Filed Aug. 29. 1927 `5 Sheets-Sheet 3 Ein ww@ N oy. 19,1929.

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Patented Nov. 19, 1925? UNITED STATES PATENT OFFICE ROBERT H. MACINNES, OF CHICAGO, lLLNOIS, ASSIGNOR TO CRIBBEN & SEXTON COM- PANY, OF CHICAGO, ILLNOIS,

A CORPORATION OF ILLINOIS ELECTRIC OVEN Application 'led August 29, 192i?. Serial No. 216,140.

proved and simplified construction, the parts whereof can be made in the simplest man: ner and the assembly of which can be eiiected cheaply and easily.

m The invention is illustrated in a preferred embodiment in the accompanying drawings,

in which- Fig. l is a plan view of a heating-element for an oven constructed in accordance with the invention; Fig. 2,'an elevational view of the same with resistance-coils omitted; Fig;

3, a broken vertical sectional view taken as indicated at line 3 of Fig.v l; Fig.l 4, a

.broken transverse sectional view taken as" indicated at vline 4 of Fig. 3; Fig. 5, a plan view 'ofa supporting-block employedV for strin 'ng the resistance-wire coil; Figs.` 6 -and front and rear views of the same, respectively; Fig. 8, a side elevational view of the same; Fig. 9, -a broken bottom plan view illustrating the manner in which the shank of the supporting-block interlocks with the socket, or slot, of the mounting-plate; Fig. l0, a broken vertical sectional view of the improved oven and heating element therein; Fig. `1l, a broken bottom plan view `of the heating element; and Fig. 12,y a plan view of the interchangeable insulation-block used `as a means for" mounting the 'switchjacks in the oven and used also as a means formounting the switch-plugs on the heating element. s

In the construction illustrated, A designates an oven equipped with a door A; B designatesa heating element which comprises a mounting-plate B, resistance-coil supporting-blocks B2, a resistance-coil B3, an insula- The heating. element B may be removed from the oven at will. The mounting-plate B preferably consists of a steel-plate which is, so stamped as to provide a marginal portion l and a raised body-portion 11 which is provided with interlock-slots, or sockets, lb. These sockets are arranged in longitudinal and transverse rows, except that at the end-portions of the plate certain sockets may be disposed between the longitudinal rows for the purpose of receiving the supporting-blocks for loops of the resistance- Coil. The 'mounting-frame is showinl provided at its front end with a flange 1 which may serve as a handle when it is desired to withdraw the heating element from the oven.l

The supporting-blocks B2 are all alike. Each block (see Figs. 5-8) comprises a headportion 2 and a reduced shank-portion 2a provided with interlock-flanges 2'?, forming an elongated head for the shank.A The shank may be inserted through the slots 1b, and the block may then be partially rotated to eiiect the interlocking engagement.

The head 2 of each supporting-block is provided witha pair of channels 2c extending therethrough in substantially parallel relation. These channels arelaterally open at 'the tortuous paths indicated at 2d. As thus described, each channel 2C is partially bound at its outer side by diagonally opposite flanges, or retainer-lips, 2e and 2f, the former of which is a depending lip and the latter an upstanding lip. These retainerlips prevent later displacement of the resistance-coil after it has been entered in the channel. The head of the block BZ is also provided at its upper portion with a channel 2g which intersects the two channels 2c,

`the end-portions of the channel 2g aiiording portions of the laterally open tortuous channels 2d.l The channel 2g is covered by a central tongue 2h which is midway betweenthe j two upturned flanges 2f. The channel 2g is open at the front face of the block, as indicated at 2i. y

The resistance-wire is strung upon the supporting-blocks in the manner illustrated in Fig. l. Thus, two adjacent 'strands 3 of the resistance-coil extend through the path of parallel channels 2C of a longitudinal row 'of supporting-blocks. The strands may be introduced into the channels by lateral movement, the coil being kinked in a Vertical plane as may be necessary to pass over the upstand' ing retainer-lip 2f and under the depending retainer-lip 2"'.

Where the resistance-,coil turns a cornerI` or Where a loop of tlie resistance-coil is to be supported, the coil is passed under the tongue 2 so as to engage the channel 2g. Thus, in Fig. 1, the corner portions of tlieloop 3a are shown engaging the channels 2f? of two of the 'supporting-blocks; and the shorter loop 3" is shown passed beneath the tongue@h and thus engaging the channel 2g. In this instance, the coil alsoextends through portions of the channels 2'. j

The insulation-block B4, which is the saine in form and is interchangeable with the insulation-block C, is shown as consisting of an elongated rectangular block provided at its upper side and ends with a peripheral groove 4 which is engaged by a metal strap 5 whose ends are secured to the mounting-plate by means of bolts 6. The strap, or stirrup', 5 is provided with flanges 5a adapted to serve as guards. To the upturned flange 5ZL is secured a, guard-plate 7 which extends rearwardly to the inner rear wall of the oven, as shown in Fi .10.

he insulation-block B* is provided at its lrpnt and rear faces with longitudinal projections I8 which serve the function of engaging slots with which the spaced rear walls of the v n are provided, when the block is em- /ployed at the'position C.

\ The insulation-block is provided with a l series of sockets 9 which are of square or annular cross-section. These sockets preferably extend somewhat more than half way through the block and are in alignment with perforations 9a. The Iblock is provided also with perforations 10 through which the wires leading from the resistance-coils may pass.

When the insulation-block is used, as indicated at B4, the squared sockets 9 serve to receive the shank-portions of the switch-plugs B6. These shank-portions are designated 1l and are provided with tapped bores which are engaged by screws 12 extending through the perforations 9a. The Shanks 1l' are equipped with headsV 11n provided with tapped openings which receive the threaded shanks of the blade-portions 1.3 of the switchplugs B8. Extending yvertically through the head 11a is a perforation 14 in which the wire from the resistance-coil is entered. The wire is clamped into the passage 14 by means of the threaded shank ofthe blade 13. As will be understood from Fig..3, the wire passes from the resistance-coil through the passage 10 and then into the passage 14 where it is secured. Y

As appears from the right-hand portion ot the block B4 is interposed betweenl the inner wall 15 andouter wall 16 of the oven, and the projections 8 extend through slots with which said walls are provided,` the block being thus anchored in position. The block is turned end for end in this position, so that the sockets' 9 are turned forwardly. The jacks 17 are mounted in the sockets and secured i-n position by means of screws 18 which extend through the perforations 9a. With the screws, or bolts, 18 are connected wires 19 which lead to suitable switches (not shown). In front of the wall 15 is disposed a block 20 which is secured in position by any suitable means (not shown). The block 20 is provided with guide-perforations 20.CL through which the switch-,plugs enter when the heating element is placed in position in the oven. Ordinarily, provision is made for using any oneof three heats in the oven. This is accomplished by suitable arrangement of the portionsof the resistance-coil and suitable switch connections, so that all portions of the resistance-coil can be used in series, two portions may be used in parallel, or one portionl may be used alone. In the illustration given, the-resistance-coil is s hown arranged to enable the result mentioned to be obtained.

From the description given, it will be nnderstood that the heating element is of very simple construction, the parts may be manufactured at moderate cost, and the assembly may be readily and cheaply effected. .The

supporting-blocks for the resistance-wire are molded, or pressed, from a suitable compound. When desired, the adjacent strands' 3 may be disconnected from an intervening supporting-block, the block may be rotated to a position at right angles' to the position shown and thereupon may be removed. Thus, replacements may be readily made.

The feature of making the blocks B4 and C interchangeable also contributes to the cheapness of manufacture. This feature effects a saving in dies, ormolds, enables a stock of partsr to be kept at a moderate amount, and prevents mistakes in assembly.

It is true, also, that by using a single form 1 of supporting-block for the resistance-wire, the stock of parts may be smaller, the assembling operation is rendered more rapid, and chances for errors are eliminated.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but thel appended claims should be construed as broadly as permissible, in view of the prior art.

What I regard .as new, and desire to secure by Letters Patent, is:

1. An electric heating element comprising a mounting-plate, and supporting-blocks provided with Shanks removably and interlockingly connected with said mountingi Fig. 10, the block C which corresponds with plate, each of said blocks having a headportion provided with a pair of laterally Iopen channels extending in one direction and equippedwitli retainer-lips and having an intersecting channel open at one side.`

2. An electric heating element comprising a inounting-plate provided with interlock` sockets; a plurality of rows of supportingblocks having shank-portions interlocking with said sockets, and having head-portions provided with a pair ot laterally open channels extending in one direction and an intersecting channel `which is open at one side; a resistance-coil having' strands flanking the rows of supporting-blocks, apair of said' strands engaging the pairs of vchannels through said blocks, said resistance-coil presenting loops and curves; and supportingblocks of the saine construction as the first mentioned blocks but having theirintersecting channels engaged by the loops and curves of said resistance-coil.'

3. In an oven, -the combination with a pair of spaced walls of said oven, of an interposed insulation-block having projections engaging slots in said walls, said block having sockets opening at the front side of Vthe block and having reduced perforations extending from said sockets through the rear side of the block, switch jacks in said sockets, and bolts extending through said perforations and securing said jacks in said sockets.

4. In an oven, the combination with a pair of spaced walls of said oven, of an interposed insulation-block-having projections engaging slots in said Walls, said block having sockets opening at the front side of the -block and having reduced perforations extending from said sockets through the rear side of the block, switch jacks in said sockets, bolts extending through said perforations 1 and securing said jacks in said sockets, and a block disposed in front of-the inner wall .of said oven and provided with guidefper- 1 foratioiis registering withthe spaces of said jacks which are adapted to receive the coni tact-plugs of the heating element.

5. An interchangeable insulation-block for the purpose set forth, said block having its front and rear portions provided with projections and having sockets open at one' face of the block and perforations'extending from said 'sockets and opening at the other face of the block, contact-members in said' sockets, and connections extending through said perforations and securing said contact-members in position.

6. Inmeans of the character set forth, an

insulation-block provided with sockets open- Aci ing at one face of the block and perforations extending from said sockets and opening at@ the other face of the block; and switch-plugs and switch-j acks interchangeably adapted to said sockets.

7. An electric oven having a pair of spaced walls, an insulation-block interposed between said walls and interlockingly connected therewith, said block having sockets opening in to said oven and pertorations extending troni said sockets to the opposite tace ot said block, jacks mounted in said sockets, bolts extending through said pertorations and securing said jacks in position; and a heating elenient mounted in said oven comprising a mounting-plate, supporting-blocks thereon,

a resistance-coil strung on said blocks, an 

